Poly (phenylene ether) resin composition, prepreg, and laminated sheet

ABSTRACT

An object of the invention is to provide a poly(phenylene ether) resin composition that allows production of laminated sheets excellent in heat resistance and processability, even in case of using a low molecular weight PPE for convenience in prepreg manufacturing without the sacrifice of dielectric characteristics. 
     The poly(phenylene ether) resin composition according to the present invention comprises poly(phenylene ether) and a crosslinking curing agent, wherein the poly(phenylene ether) is represented by the following formula (I) and the number averaged molecular weight thereof is in the range of 1,000 to 7,000. 
     
       
         
         
             
             
         
       
     
     [wherein, X is an aryl group; (Y) m  is a poly(phenylene ether) moiety; Z is a phenylene group and the like; R 1  to R 3  each independently is a hydrogen atom, and the like; n is an integer of 1 to 6; and q is an integer of 1 to 4.]

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of application Ser. No. 10/718,525,filed Nov. 24, 2003, the disclosure of which is incorporated byreference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to heat-resistant/ly(phenylene ether)(hereinafter, referred to as PPE) resin compositions useful asinsulation materials for printed wiring boards or the like, prepregsusing the PPE resin compositions, and laminated sheets using theprepregs.

2. Description of the Related Art

Recently, along with the progress in technology for integration ofsemiconductor devices used in electronic devices, higher densityelectronic packages, and higher density wiring of printed wiring boards,as well as in junction and mounting technologies, there have beencontinuous advances made in electronic devices, and in particular somestartling advances in the electronic devices that uses broadband, suchas mobile communication devices.

Printed wiring boards, a constituent for such electronic devices, areheading toward more highly multilayer boards and more concise finerpitch wiring simultaneously. It is effective to reduce the dielectricconstant of the materials used therein for raising signal transmissionspeed to the level needed for acceleration of information processing,and to use materials with a lower dielectric dissipation factor(dielectric loss) for reducing transmission loss.

Accordingly, PPE resins are suitable as a material for the printedwiring boards used in the electronic devices that utilize broadband, asPPE resins have favorable high frequency characteristics (dielectriccharacteristics) for example in dielectric constant, dielectric loss,and the like. However, PPE resins were not so far sufficiently high inheat resistance and dimensional stability. In addition, these PPE resinscarry the disadvantage that they generally have a high melting point,and the use of such a PPE resin for production of prepregs for ordinarymultilayer printed wiring boards often resulted in increase in meltviscosity of the prepreg, causing processing defects such as voids andscratches during production of the multilayer sheets and providingmultilayer sheets not highly reliable in quality.

PPE resin compositions aimed at improvement in heat resistance anddimensional stability, prepregs using the PPE resin compositions, andlaminated sheets using the prepregs were disclosed in JapaneseUnexamined Patent Publication No. 8-231847. They are respectively thePPE resin compositions containing PPE, triallyl isocyanurate andnonreactive brominated compound; the prepregs using the PPE resincompositions; and the laminated sheets using the prepregs.

However, when the resin composition described in Japanese UnexaminedPatent Publication No. 8-231847 was used, it was difficult to producemultilayer sheets, as the PPE per se has a high melting point and thusthe melt viscosity of the resin composition is too high at ordinaryheat-pressing temperature to interpose internal conductive patternedlayers into the multilayer printed wiring board.

Alternatively, PPE resin compositions comprising a PPE having a smallermolecular weight and thus better fluidity of the melt resin duringprocessing and an improved processability at ordinary heat-presstemperature, the prepregs using the PPE resin compositions and thelaminated sheet using the prepregs are proposed in Japanese UnexaminedPatent Publication No. 2002-265777. The PPE resin compositions describedtherein was effective in improving the efficiency of producingmultilayer sheets.

And U.S. Pat. No. 6,352,782 discloses PPEs, of which the terminalhydroxyl group is capped with the group represented by the followingformula. Even though the molecular weight of the PPEs used are notdefinitely described at all in the EXAMPLEs therein, the number averagedmolecular weight of the PPE is described as preferably less than 10,000and in particular about 300 to 5,000 (still more preferably about 500 to5,000).

As described above, it is effective to reduce the molecular weight ofPPEs in order to raise the fluidity of melt PPE resins and thus theefficiency of prepreg production.

However, the reduction in molecular weight of PPEs is also accompaniedwith a problem of the decrease in heat resistance of the resultinglaminated sheets. Although it may be possible to increase the amount ofa crosslinking curing agent, triallyl isocyanurate, for prevention ofthe decrease in heat resistance, it also accompanies the decrease inrelative content of the PPE having excellent dielectric characteristics,making it difficult to produce lower dielectric constant products.Incidentally, the laminated sheets prepared by using the compositionsdescribed in Japanese Unexamined Patent Publication No. 2002-265777above have a dielectric constant of 3.5 to 3.7 (1 MHz) when combinedwith an E-glass cloth, and of 3.3 to 3.5 (1 MHz) when combined with anNE-glass cloth.

In this context, there exist a need for products having further lowerdielectric constant, to cope with the recent drastic increase in theamount of information processed in broadband devices.

BRIEF SUMMARY OF THE INVENTION

The present invention was accomplished considering the environmentdescribed above, and an object of the present invention is to provide apolyphenylene ether) resin composition that can give highly heatresistant laminated sheets using a PPE lower in molecular weight but yetretaining favorable dielectric characteristics, and a prepreg using thesame poly(phenylene ether) resin composition. Another object of thepresent invention is to provide a laminated sheet excellent both indielectric characteristics and heat resistance.

In order to solve the problems above, the present inventors haveconducted intensive studies on the relationship between the structureand dielectric characteristics of these materials by synthesizingvarious PPEs. As a result, it was found that modification of PPEterminal hydroxyl group with a particular group can raise efficiency ofthe reaction between PPE and crosslinking curing agent, and that evenwhen a relatively low molecular weight PPE is used for the purpose ofincreasing the fluidity in a molten state, it is possible to prepare aPPE resin composition excellent in dielectric characteristics and havinga higher glass transition temperature without the sacrifice of PPE'sinherent characteristics. And using the PPE resin composition, a prepregand laminated sheet excellent in quality can be produced.

Namely, the poly(phenylene ether) resin composition according to thepresent invention is a composition comprising a poly(phenylene ether)and a crosslinking curing agent, wherein the poly(phenylene ether) isrepresented by the following formula (I) and the number averagedmolecular weight thereof is in the range of 1,000 to 7,000.

[wherein, X is an aryl group; (Y)_(m) is a polyphenylene ether moiety; Zis a phenylene group, an oxygen atom or a sulfur atom; R¹ to R³ eachindependently is a hydrogen atom, an alkyl group, an alkenyl group oralkynyl group; n is an integer of 1 to 6; and q is an integer of 1 to4.]

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments and advantageous effects of the presentinvention will be described.

The “aryl group” according to the present invention means an aromatichydrocarbon group. These aryl groups include, for example, phenyl,biphenyl, indenyl, and naphthyl groups, and the preferred aryl group isa phenyl group. In addition, the groups wherein multiple aryl groups arebonded together, for example, those bonded via an oxygen such as adiphenylether group or the like; those bonded via a carbonyl group suchas benzophenone group or the like; and those bonded via an alkylenegroup such as 2,2-diphenylpropane group or the like, are also includedin the definition of the aryl group of the present invention. And thesearyl groups may be further substituted by one or more substituent(s),such as an alkyl group (preferably, C₁-C₆ alkyl group; in particular,methyl group), alkenyl group, alkynyl group, halogen atom, or othercommon substituting group. As the aryl group is bound via an oxygen atomto a poly(phenylene ether) moiety, the upper limit number of thesubstituting groups depends on the number of the poly(phenylene ether)moiety.

The “poly(phenylene ether) moiety” consists of phenyloxy recurring unitsand the phenyl group thereof may also be substituted by commonsubstituting groups. Such poly(phenylene ether) moieties include, forexample, the compounds represented by the following formula (II).

[wherein, R⁴ to R⁷ each independently is a hydrogen atom, an alkylgroup, an alkenyl group, an alkynyl group or an alkenyl carbonyl group;and m is an integer of 1 to 100.]

Herein, the presence of unsaturated hydrocarbon-containing groups suchas vinyl, 2-propylene (allyl), methacryloyl, acryloyl, 2-propyne(propargyl) groups or the like as side-chains of the poly(phenyleneether) moiety is effective for further raising the operation and effectof the crosslinking curing agent.

Here, m should be adjusted so that the number averaged molecular weightof the poly(phenylene ether) (I) falls in the range of 1,000 to 7,000.

The “alkyl group” means a saturated hydrocarbon group, preferably aC₁-C₁₀ alkyl group, more preferably d C₁-C₆ alkyl group, still morepreferably a C₁-C₄ alkyl group, most preferably a C₁-C₂ alkyl group.Such alkyl groups include, for example, methyl, ethyl, propyl,isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, and hexylgroups.

The “alkenyl group” means an unsaturated hydrocarbon group containing atleast one carbon-carbon double bond in its structure, and is preferablya C₂-C₁₀ alkenyl group, more preferably a C₂-C₆ alkenyl group, mostpreferably a C₂-C₄ alkenyl group. These alkenyl groups include, forexample, ethylene, 1-propylene, 2-propylene, isopropylene, butylene,isobutylene, pentylene, and hexylene.

The “alkynyl group” means an unsaturated hydrocarbon group having atleast one carbon-carbon triple bond in its structure, and is preferablya C₂-C₁₀ alkynyl group, more preferably a C₂-C₆ alkynyl group, mostpreferably a C₂-C₄ alkynyl group. These alkynyl groups include, forexample, ethyne, 1-propyne, 2-propyne, isopropyne, butyne, isobutyne,pentyne, and hexyne.

The “alkenyl carbonyl group” is a carbonyl group substituted with theaforementioned alkenyl group, and is, for example, an acryloyl ormethacryloyl group.

In PPE (I), n is preferably an integer of 1 to 4; more preferably, 1 or2; and most preferably, 1. In addition, q is preferably an integer of 1to 3; more preferably, 1 or 2; and most preferably, 1. Although m may bean integer of 1 to 100, m should be adjusted according to the numberaveraged molecular weight of the desired PPE (I), as the number averagedmolecular weight of PPE (I) should be at least 1,000 to 7,000 accordingto the present invention. That is, although the molecular weight of aparticular PPE (I) may be less than 1,000 or more than 7,000 accordingto the value of m, the number averaged molecular weight of entire PPEs(I) contained in the PPE resin composition should be 1,000 to 7,000according to the present invention, and thus m needs not to be aparticular fixed value but may vary in a certain range.

In the following partial structure of PPE (I), it is preferable that Zis a phenylene group and n is 1 (i.e., benzyl derivative), or that Z isan oxygen atom and n is 2, more preferably a p-ethenybenzyl,m-ethenybenzyl, or ethenyloxyethyl group.

PPEs (I) having these group(s) at the terminal(s) thereof have aparticularly favorable interaction with a crosslinking curing agent, andallow production of low-dielectric constant products even without theneed for adding a great amount of the crosslinking curing agent. Inparticular, PPEs having both p-ethenybenzyl and m-ethenybenzyl groups attheir terminals have low melting and softening points, while thosehaving only p-ethenybenzyl groups at their terminals have high meltingand softening points. Accordingly, it become possible to control themelting and softening points of PPEs arbitrarily by adjusting the ratioof the p-ethenybenzyl and m-ethenybenzyl groups.

The number averaged molecular weight of PPE (I) is 1,000 to 7,000. It isbecause when a PPE having a molecular weight of over 7,000 is used, thedecrease in fluidity during processing of the PPE makes multilayerprocessing more difficult, and when a PPE having a molecular weight ofless than 1,000 is used, the resulting prepregs and laminated sheets donot always exhibit the favorable dielectric characteristics and heatresistance inherent to PPE resins. In order to make PPE resins exhibitthe excellent fluidity, heat resistance and dielectric characteristics,the number averaged molecular weight thereof is preferably 1,200 andabove, 5,000 and below, more preferably 1,500 and above, 4,500 andbelow.

Additionally, PPE (I) with a smaller molecular weight drasticallyimproves the compatibility thereof with a crosslinking curing agent whenthey are blended. That is, the smaller the molecular weight of PPE (I),the better the compatibility of the blended components. Accordingly,such lower molecular weight PPEs prevent increase in viscosity due tophase separation, suppress volatilization of the low molecular weightcrosslinking curing agent, and thus improve resin hole-filling propertyinto inner via holes (hereinafter, referred to as IVH) particularly. Inparticular, the blending ratio of PPE (I) to the crosslinking curingagent is preferably 30/70 to 90/10 by mass part. Namely, with thecontent of PPE (I) at less than 30 mass parts, the laminated sheetsprepared may become brittle, while with the content of PPE (I) at morethan 90 mass parts (the content of crosslinking curing agent being lessthan 10 mass parts), the laminated sheets may have a decreased heatresistance.

Hereinafter, the method for producing PPE (I) will be described.

Hitherto, PPEs have been produced by, for example, the method disclosedin U.S. Pat. No. 4,059,568 and the number averaged molecular weight (Mn)thereof is generally 13,000 to 25,000. However, PPEs have inherently ahigh resin melting point and a melt viscosity, carrying the problems ofprocessing defects when used as the material for multilayer printedwiring boards. So, reduction in molecular weight of the PPEs permitsreduction in resin viscosity and improvement in processability.

According to Japanese Unexamined Patent Publication No. 2002-536476 (thecontents of which are hereby incorporated by reference), low molecularweight PPEs may be isolated and obtained by a variety of methods but areusually isolated and obtained by precipitation with a suitable reactiveagent. As the method for reducing molecular weight of PPEs, may be usedthe method described in The Journal of Organic Chemistry, 34, 297-303(1969) (the contents of which are hereby incorporated by reference).This method uses a reaction of a phenol species with PPEs for reductionin molecular weight of the PPEs. The phenol species to be used in thisreaction includes phenol, cresol, xylenol, hydroquinone, bisphenol A,2,6-dimethylphenol, 4,4′-dihydroxydiphenyl ether or the like, but theuse of a phenol species having 2 or more functionalities is preferredfor improvement in heat resistance of the products after curing.Additionally, as the initiator of the reaction, the use of an oxidizersuch as benzoylperoxide, 3,3′,5,5′-tetramethyl-1,4-diphenoxyquinone,chloranil, 2,4,6-tri-t-butylphenoxyl, t-butylperoxyisopropylmonocarbonate and azobisisobutylonitrile is preferable, and a metalcarboxylate salt may also be added to promote the reaction if desired.In addition, compounds that generate volatile components such as lowmolecular weight alcohols after the reaction are more preferably used asthe initiator for the purpose of suppressing increase in dielectricconstant.

The reaction for low molecular weight PPEs is conducted by adding a highmolecular weight PPE (common PPE having a number averaged molecularweight of more than 10,000), a phenol species and an initiator in asolvent and heating the mixture. Cobalt naphthenate or the like may beadded to the mixture as a catalyst. The solvent use therein is notparticularly limited if the solvent can dissolve these components to asuitable extent and does not interfere with the reaction, and, forexample, aromatic hydrocarbon solvents such as benzene, toluene or thelike may be used as the solvent. The reaction temperature and time mayvary according to the number averaged molecular weight or the like ofthe desired PPEs, but is, for example, at 60 to 100° C. for 30 minutesto 6 hours. These reaction conditions may be determined by conductingpreliminary experiments. After the reaction, the low molecular weightPPEs may be used directly in the following reaction processes just bydistilling the solvent off under reduced pressure. Alternatively, theymay be partially purified by adding a poor solvent for PPEs such asmethanol into the reaction mixture and precipitating the desired PPEs.

The PPEs obtained by the reaction above are suitably lower in molecularweight by the cleavage of polymer backbones during the reaction, andcontain an aryl group derived from the phenol species used at one endand a hydroxyl group at the other end represented by the followingformula. In the formula, the number of poly(phenylene ether) moietiesper phenol species, i.e., q, is dependent on the number of hydroxylgroups in the phenol species used. That is, when the phenol species hasonly one hydroxyl group, q is 1, and when a polyvalent phenol is used asthe phenol species, q becomes 2 or more.

[wherein, X, (Y)_(m), and q have the same meanings as described above.]

Subsequently, the terminal hydroxyl groups are capped according to thefollowing reaction formula.

[wherein, X, (Y)_(m), Z, R¹ to R³, m, n, and q have the same meanings asdescribed above; and, Hal represents a chlorine or bromine atom.]

In the reaction above, the terminal hydroxyl groups are capped byreacting the PPE obtained by the lowering molecular weight reactionabove with a halogenated compound such as chloromethylstyrene or thelike in the presence of a base in a solvent. An alkali metal hydroxidesuch as sodium hydroxide or the like may be used as the base. In such acase, a base such as an aqueous sodium hydroxide solution is added to asolution of a low molecular weight PPE in a solvent such as toluene orthe like, and quaternary ammonium salt (e.g., tetra-n-butylammoniumbromide) may additionally added as a phase transfer catalyst to promotethe reaction. The reaction temperature and time may mainly varyaccording to the kind of compounds used, and is, for example, at roomtemperature to 100° C. for 30 minutes to 10 hours. After the reaction,the desired product can be obtained by precipitating the product byadding a poor solvent for the desired product, for example, water, alower alcohol such as methanol or the like; filtering; washing with thesame solvent; and drying.

The inventive PPEs thus obtained, as they are lower in molecular weight,provide PPE resin compositions excellent in fluidity. In addition, asthe PPEs can be easily cured with a relatively small amount ofcrosslinking curing agent, the use of the PPEs according to the presentinvention in an amount as much as allows can improve dielectriccharacteristics of the resulting PPE resin compositions and retain thePPE's inherent characteristics such as heat resistance and the like.

The crosslinking curing agent added to the PPE resin composition of thepresent invention is primarily for crosslinking the poly(phenyleneether)s of the present invention described above three dimensionally.And even when the low molecular weight poly(phenylene ether) is used inthe PPE resin compositions for increasing fluidity, the crosslinkingcuring agent can retain heat resistance or the like of the PPE resins.Crosslinking curing agents excellent in compatibility with PPEs areespecially used as the crosslinking curing agent in the presentinvention, and preferable examples thereof include, multifunctionalvinyl compounds such as divinylbenzene, divinylnaphthalene,divinylbiphenyl or the like; vinylbenzylether compounds prepared in thereaction of phenol and vinylbenzylchloride; allylether compound preparedin the reaction of styrene monomer, phenol and allylchloride; andtrialkenylisocyanurates. In particular, trialkenyl isocyanurates thatare excellent in compatibility are favorable, and among them,triallylisocyanurate (hereinafter, TAIC) and triallylcyanurate(hereinafter, TAC) are preferred. It is because these two crosslinkingcuring agents give laminated sheets having a lower dielectric constantand excellent in heat resistance and reliability.

Alternatively, the use of a (meth)acrylate compound (methacrylate oracrylate compound) as the crosslinking curing agent of the presentinvention is also favorable. And in particular, the use of a tri- topenta-functional (meth)acrylate compound in an amount of 3 to 20 mass %with respect to the total amount of PPE resin composition is preferred.As the tri- to penta-functional methacrylate compound,trimethylolpropane trimethacrylate (TMPT) or the like may be used, whiletrimethylolpropane triacrylate or the like may be used as the tri- topenta-functional acrylate compound. Addition of these crosslinkingcuring agents further increases the heat resistance of the laminatedsheets finally obtained.

While (meth)acrylate compounds having functional groups fewer or morethan 3 to 5 may be used, the use of tri- to penta-functional(meth)acrylate compounds increases the heat resistance of the resultinglaminated sheet to the larger extent. Even when a tri- topenta-functional (meth)acrylate compound is used, the use of thiscompound in an amount of less than 3 mass % with respect to the totalamount of the PPE resin composition may not provide the final laminatedsheets with sufficient heat resistance, while the use in an amount ofmore than 20 mass % may reduce the dielectric characteristics andhumidity resistance of the final laminated sheets.

The blending ratio of PPE to the crosslinking curing agent is preferably30/70 to 90/10 by mass part. Only less than 30 mass parts of the PPE maymake the laminated sheets more brittle, while the presence of the PPE atmore than 90 mass parts may reduce the heat resistance thereof. Namely,in order to prevent decrease (difficulty) in resin hole-filling propertyinto IVH due to compatibility that depends on the molecular weight ofPPE and on the blending ratio of PPE to a crosslinking curing agent suchas triallylisocyanurate, the blending ratio of PPE to crosslinkingcuring agent may be determined as described above in the presentinvention. In addition, a blending ratio of PPE to crosslinking curingagent in this specified range allows improvement in fluidity andcompatibility of the PPE resin compositions and at the same timeimprovement in dielectric characteristics of the PPE resins obtained.The blending ratio of PPE to crosslinking curing agent is preferably50/50 to 90/10, more preferably 60/40 to 90/10.

In addition, the use of the above mentioned PPE combined with anunmodified PPE having a number averaged molecular weight of 9,000 to18,000 in the PPE resin composition according to the present inventionallows further improvement in fluidity control and heat resistance ofthe PPE resin composition concerned in the present invention.Additionally, it also suppresses precipitation of additive componentssuch as filler and the like in the composition. Incidentally, theunmodified PPEs are poly(phenylene ether)s having no unsaturatedcarbon-carbon groups in the molecule, and the blending amount thereof ispreferably 3 to 70 mass parts with respect to the total amount of PPEand the crosslinking curing agent.

Further, in order to improve heat resistance, adhesive property, anddimensional stability, at least one compatibilizer selected from thegroup consisting of styrene-butadiene block copolymers, styrene-isopreneblock copolymers, 1,2-polybutadiene, 1,4-polybutadiene, maleicacid-modified polybutadiene, acrylic acid-modified polybutadiene, andepoxy-modified polybutadiene may be used if desired in addition to thisPPE.

The PPE resin composition according to the present invention may furthercomprise, if desired, inorganic and organic fillers. The inorganicfiller can be used for suppressing the thermal expansion coefficient andimproving the toughness of the laminated sheets prepared from the PPEresin composition of the present invention. The inorganic filler to beused is not particularly limited, but metal oxides, nitrites, silicides,borides or the like such as silica, boron nitride, wollastonite, talc,kaolin, clay, mica, alumina, zirconia, such as titania, etc. areexemplified. The PPE resin composition according to the presentinvention is effective for reducing dielectric constant, and thus theuse of low-dielectric constant fillers such as silica and boron nitrideis preferred as the inorganic filler.

On the other hand, organic fillers are used primarily for the purpose ofreducing the dielectric constant of laminated sheets prepared from thePPE resin compositions of the present invention. Specifically,fluorine-based, polystyrene-based, divinylbenzene-based, polyimide-basedfillers or the like are exemplified, and these fillers each may be usedalone or in combination.

Examples of the fluorine-based fillers (fillers made offluorine-containing compounds) include polytetrafluoroethylene (PTFE),polyperfluoroalkoxy resins, polyethylenefluoride-propylene resins,polytetrafluoroethylene-polyethylene copolymers, polyvinylidenefluoride, polychlorotrifluoroethylene resins or the like. Theseinorganic and organic fillers each may be used alone or in combination.

The aforementioned fillers should be pulverized into particles smallerin size for the purpose of improving insulation characteristics andreliability to cope with a recent trend toward lighter, thinner,shorter, and smaller products and high-density mounting. Morespecifically, the fillers are preferably fine particles having a averagediameter of not more than 10 μm. Such fillers allow production oflaminated sheets excellent in evenness and reliability. The “averagediameter” is not necessarily determined but may be decided by thebrochure about the filler. Most of the fillers currently available arefine particles having an average diameter of 0.05 μm or more, and thusthe lower limit of the average diameter of fillers is essentially thisvalue.

The inorganic and organic fillers used for the PPE resin compositionaccording to the present invention may be hollow or porous particles, orparticles made of a fluorine-containing compound for the purpose offurther reducing the dielectric constant of the products. It is becausethese fillers allow production of laminated sheets excellent indielectric constant.

In the case of inorganic hollow particles, the sintering temperaturethereof is important and preferably 600° C. or more. When the hollowparticles are prepared by the sol-gel method or the like, such hollowparticles may deteriorate dielectric characteristics, and in particularraise dielectric dissipation factor due to residual silanol groupsthereon and may drastically deteriorate broadband characteristic.

In the case of organic fillers, the hollow polymeric fine powdersdisclosed in Japanese Unexamined Patent Publication No. 2062-80503 (thecontents of which are hereby incorporated by reference) are useful. Theshell for the hollow particles is made of a low-dielectric constantmaterial such as divinylbenzene or divinylbiphenyl, which isadvantageous for producing laminated sheets having a low-dielectricconstant.

The PPE resin compositions according to the present invention mayfurther contain, if desired, a flame retardant for the purpose ofincreasing the water resistance, humidity resistance, heat and moistureresistance, and glass transition point of laminated sheets. In such acase, in a varnish consisting of the PPE resin composition containingthe PPE, a crosslinking curing agent and a flame retardant; and asolvent (organic solvent), the aforementioned flame retardant ispreferably a bromine compound that is nonreactive to the PPE and thecrosslinking curing agent and not soluble but dispersed in the solventused for the varnish. Namely, when the flame retardant is a reactiveflame retardant having unsaturated bonds, or a flame retardant solublein the aforementioned solvent, the flame retardant is incorporated intothe reaction system for production of the matrix resin, consequentlyreducing the water resistance, humidity resistance, heat and moistureresistance and glass transition point (hereinafter, referred to as Tg)of the prepreg using this resin composition and the laminated sheetusing the prepreg. Therefore, when the flame retardant is a brominatedorganic compound nonreactive with PPE and the crosslinking curing agentand is not soluble but dispersed in the solvent, the flame retardantseemingly remains in the resin as a filler, improving the waterresistance, humidity resistance, heat and moisture resistance and Tg ofthe products. In addition, the true specific gravity of the brominatedorganic compound is preferably in the range of 2.0 to 3.5. When the truespecific gravity of the flame retardant, a brominated organic compound,is less than 2.0, the flame retardant can be hardly dispersed, whilewhen the specific gravity is over 3.5, the flame retardant tends tosediment in the varnish of the PPE resin composition and requirescontinuous stirring to keep the varnish homogenous, thus reducingoperational efficiency.

As such a brominated organic compound, an aromatic bromine compound ispreferable, and suitable examples thereof include decabromodiphenylethane, 4,4-dibromobiphenyl, ethylene bistetrabromophthalimide, or thelike. The brominated organic compound is preferably contained in such anamount that the content of bromine falls in the range of 8 to 20 mass %with respect to the total amount of the resin composition. When thecontent of bromine is less than 8 mass % with respect to the totalamount of the resin composition, the laminated sheets have a declinedflame resistance and cannot retain the flame resistance at the level ofUL Standard 94V-0, while when the content exceeds 20 mass %, thelaminated sheets have a declined heat resistance and release bromine(Br) more easily when the laminated sheets are heated.

In addition, the PPE resin composition according to the presentinvention may further comprise a reaction initiator for the purpose ofenhancing the advantageous effect of the crosslinking curing agent.Although the presence of PPE (I) and a crosslinking curing agent alonecan advance curing at high temperature, it is desirable to add thereaction initiator as it is sometimes difficult to keep high temperatureuntil the curing is completed depending on the process conditions. The“reaction initiator” is not particularly limited if it can acceleratecuring of the PPE resin compositions at a suitable temperature andwithin a suitable period, and increase the characteristics such as heatresistance or the like of the PPE resin; and examples thereof areoxidizers such as α,α′-bis(t-butylperoxy-m-isopropyl)benzene,2,5-dimethyl-2,5-di(t-butyl peroxy)-3-hexyne, benzoylperoxide,3,3′,5,5′-tetramethyl-1,4-diphenoxyquinone, chloranil,2,4,6-tri-t-butylphenoxyl, t-butylperoxyisopropyl monocarbonate,azobisisobutylonitrile. And if desired, the curing-reaction may furtheraccelerated by further adding a metal carboxylate salt. Among them,α,α′-bis(t-butylperoxy-m-isopropyl)benzene is particularly preferable asthe reaction initiator. It is because the compound has a relatively highreaction initiation temperature, thus not initiating curing when thecuring is not required, for example, during prepreg drying, and notimpairing the storage stability of the PPE resin compositions; a lowvolatility, preventing vaporization during prepreg drying and storage;and thus an excellent stability.

As described above, the PPE resin composition according to the presentinvention requires PPE (I) and a crosslinking curing agent as essentialcomponents; preferably contains one or more components selected from thegroup consisting of unmodified PPEs, fillers, flame retardants, andreaction initiators; and further contains common additives to the PPEresin compositions for use in production of electronic devices(particularly, printed wiring boards).

The PPE resin composition according to the present invention is firstprepared as a varnish, by adding a PPE, an crosslinking curing agent,and the other additive components if desired to an organic solvent, forproducing prepregs by impregnating the vanish into substrates. Theorganic solvent is not particularly limited if it do not dissolve theaforementioned brominated organic compound but dissolves the resincomponent and does not impair the reaction; and suitable solventsinclude, for example, ketones such as methylethylketone or the like,ethers such as dibutylether or the like, esters such as ethyl acetate orthe like, amides such as dimethylformamide or the like, aromatichydrocarbons such as benzene, toluene, xylene or the like, andchlorinated hydrocarbons such as trichloroethylene or the like; eachsolvent can be used alone or in combination thereof. The concentrationof resin solid matter in the varnish may be changed suitably accordingto the process for impregnating the varnish into substrates, and is, forexample, suitably 40 to 90 mass %.

Prepregs are produced by impregnating the varnish prepared as describedabove into substrates and heat-drying the same to remove the organicsolvent and partially curing the resins in the substrates. As thesubstrate, any woven or unwoven fabrics made of known organic or glassfibers may be used, but the substrate is preferably an NE-type glasscloth, and the use thereof provides prepregs and laminated sheets lowerin dielectric constant and dielectric dissipation factor and better inhigh frequency characteristics. Here, the “NE-type glass cloth” is aglass cloth having a low dielectric constant. Namely, glass cloths madeof NE glasses having a dielectric constant (ε: 4.4) lower than that (ε:6.5) of the ordinary E glasses are called “NE-type glass clothes”. Theterm, “NE”, represents “New E-type glass”.

The amount of the varnish impregnated into the above substrate ispreferably at such an amount that the mass content of the resin solidmass in the prepreg is 35 mass % or more. The dielectric constant of thesubstrates is generally higher than that of the resins, and thus inorder to decrease the dielectric constant of the laminated sheetsprepared from these prepregs, the content of the resin component in theprepreg is preferably higher than the aforementioned mass content. Forexample, the prepregs prepared from an E glass cloth (substrate)containing a resin at a resin component content of 37 mass % or more canhave a dielectric constant of as low as 3.5 or less, while thoseprepared from an NE glass cloth containing a resin at a resin content of45 mass % or more can have a dielectric constant as low as 3.3 or less.In addition, the condition for heating the substrates impregnated withthe varnish is, for example, 80 to 150° C. for 1 to 10 minutes, but isnot restricted thereto.

In the present invention, laminated sheets may be produced using theaforementioned prepregs. More specifically, multilayered and integratedlaminated sheets having a metal foil on one side or two metal foils onboth faces can be produced by stacking one or multiple sheets of theprepregs according to the present invention, placing on one or bothsides metal foils such as copper foil or the like, and heat-pressing theresulting stack. Etching of the metal foils on the surface of thelaminated sheets to form a wiring pattern provides printed wiringboards. Further, multilayer printed wiring boards can be prepared byusing this printed wiring boards as internal layer printed wiringboards, providing a surface treatment to the metal foils thereon,stacking multiple sheets thereof while interposing a sheet of theprepreg of the present invention between them, laying metal foils on theutmost faces of the stack, and heat-pressing the resulting entire stack.The heat-pressing condition may vary according to the blending ratio ofraw materials used for production of the PPE resin compositionsaccording to the present invention and is not particularly limited, butthese stacks are preferably heat-pressed under a condition of atemperature in the range of 170° C. to 230° C. and a pressure in therange of 1.0 MPa to 6.0 MPa (10 kg/cm² to 60 kg/cm²) for a suitableperiod. The laminated sheets and printed wiring boards obtained in thismanner are excellent in high-frequency such as dielectriccharacteristics or the like without the sacrifice of the characteristicsinherent to PPEs, and are at the same time improved in processability,water resistance, humidity resistance, moisture and heat resistance, andglass transition point.

Further, the use of copper foils for production of the laminated sheetsaccording to the present invention having a surface roughness of 0 μm to2 μm; the surface thereof on which a resin layer is to be formed with aprepreg (surface contacting with prepreg) being treated with zinc or azinc alloy for corrosion prevention and improvement in adhesiveness withthe resin layer, and additionally treated with a coupling agent such asa vinyl group-containing silane coupling agent, allows production ofprinted wiring boards higher in adhesion strength between the resinlayer (insulation layer) and the circuit (copper foil) and better inhigh-frequency characteristics. For the treatment of copper foils withzinc or a zinc alloy, zinc or the zinc alloy may be deposited onto thesurface of the copper foil by means of, for example, plating.

Accordingly, the prepregs obtained by impregnating the PPE resincomposition according to the present invention into substrates andheat-drying and semi-curing the impregnated substrates, and thelaminated sheet obtained by stacking and heat-pressing a predeterminednumber of the prepregs are excellent in processability, waterresistance, humidity resistance, moisture and heat resistance, and glasstransition point; and the prepregs exhibit an excellent processabilitywhen used for production of multilayer printed wiring boards. Inaddition, the laminated sheets according to the present invention forproduction of printed wiring boards provides the printed wiring boardsthat are lower in dielectric constant and dielectric dissipation factor,higher in water resistance, humidity resistance, moisture and heatresistance, higher in glass transition point, improved in adhesionstrength, and excellent in high frequency characteristic. Alternatively,the use of the prepregs according to the present invention as alaminated sheet for production of multilayer printed wiring boardsprovides the multilayer printed wiring boards having no voids orscratches generated during the multilayer processing, excellent inprocessability, lower in dielectric constant and dielectric dissipationfactor, superior in water resistance, humidity resistance, moisture andheat resistance, higher in glass transition point, better in adhesionstrength, and improved in high frequency characteristics.

Hereinafter, the present invention will be described in more detail withreference to Examples.

EXAMPLES Preparation of Low Molecular Weight PPE (PPE-1)

First of all, the molecular weight of a PPE was adjusted.

36 Mass parts of a PPE (GE PLASTICS Japan Ltd.; brand name: “NorylPX9701”; number averaged molecular weight: 14,000), 1.54 mass parts of2,6-dimethylphenol as a phenol species, 1.06 mass parts oft-butylperoxyisopropyl monocarbonate (NOF Corporation; brand name;“Perbutyl I”) as an initiator, and 0.0015 mass parts of Cobaltnaphthenate were mixed and blended. To the mixture, 90 mass parts oftoluene was added as a solvent, and the resulting mixture was stirred at80° C. for 1 hour to disperse or dissolve the ingredients. After thereaction was completed, the PPE thus prepared was reprecipitated byadding a large amount of methanol, and after removal of impurities,dried under reduced pressure at 80° C. for 3 hours to remove the solventcompletely. The PPE obtained after this step had a number averagedmolecular weight of about 2,400 as determined by gel permeationchromatography (GPC).

Subsequently, the terminal hydroxyl group of the low molecular weightPPE (number averaged molecular weight: about 2,400) was capped with anethenylbenzyl group. Into a 1-liter three-necked flask equipped with atemperature controller, stirring equipment, cooling equipment, and adropping funnel, were added 200 g of the low molecular weight PPE(number averaged molecular weight: about 2,400), 14.51 g ofchloromethylstyrene (50/50 mixture of p-chloromethylstyrene andm-chloromethylstyrene; Tokyo Kasei Kogyo Co., Ltd.), 0.818 g oftetra-n-butylammonium bromide, and 400 g of toluene. And the mixture wasstirred until complete dissolution and heated to 75° C. The mixedsolution was added dropwise with an aqueous sodium hydroxide solution(11 g of sodium hydroxide/11 g of water) over the period of 20 minutesand stirred at 75° C. for additional 4 hours. Then, the solution in theflask was neutralized with a 10% aqueous hydrochloric acid solution, andadded with a large amount of methanol to reprecipitate theethenylbenzylated modified PPE, and the PPE was collected by filtration.The collected PPE was washed three times with a mixed solution ofmethanol and water at the ratio of 80 to 20, and dried under reducedpressure at 80° C. for 3 hours to give an ethenylbenzylated modified PPEcontaining no solvent or water. The modified PPE had a number averagedmolecular weight of about 2,700 as determined by gel permeationchromatography. Hereinafter, the PPE thus obtained will be referred toas “PPE-1”.

Preparation of Low Molecular Weight PPE (PPE-2)

First of all, the molecular weight of a PPE was adjusted. 36 mass partsof a PPE (GE PLASTICS Japan Ltd.; brand name: “Noryl PX9701”; numberaveraged molecular weight: 14,000), 1.44 mass parts of bisphenol A as aphenol species; and 1.90 mass parts of benzoyl peroxide (NOFCorporation: brand name “Nyper BW”) as an initiator were respectivelyblended. To the mixture was added 90 mass parts of toluene as a solvent,and the mixture was stirred at 80° C. for 1 hour to disperse or dissolvethe ingredients. After the reaction was completed, the PPE thus preparedwas reprecipitated by adding a large amount of methanol, and afterremoval of impurities, dried under reduced pressure at 80° C. for 3hours to remove the solvent completely. The PPE obtained after this stephad a number averaged molecular weight of about 2,400 as determined bygel permeation chromatography (GPC).

Subsequently, the low molecular weight PPE (number averaged molecularweight: about 2,400) was ethenylbenzylated in a similar manner to the“Preparation of PPE-1” above to give a modified PPE. The modified PPEhad a number averaged molecular weight of about 2,800 as determined bygel permeation chromatography. Hereinafter, the PPE thus obtained willbe referred to as “PPE-2”.

Preparation of Low Molecular Weight PPE (PPE-3)

Using a low molecular weight PPE of Asahi Kasei Corporation having anumber averaged molecular weight (Mn) of 2,100 and a ratio of weightaverage molecular weight (Mw) to number averaged molecular weight (Mn),(Mw/Mn), of 1.6, the terminal hydroxyl group thereof wasethenylbenzylated in a similar manner to the “Preparation of PPE-1”above to give a modified PPE. The modified PPE had a number averagedmolecular weight of about 2,500 as determined by gel permeationchromatography. Hereinafter, the PPE thus obtained will be referred toas “PPE-3”.

Preparation of Low Molecular Weight PPE (PPE-4)

Using a low molecular weight PPE of Asahi Kasei Corporation having anumber averaged molecular weight (Mn) of 2,100 and a ratio of weightaverage molecular weight (Mw) to number averaged molecular weight (Mn),(Mw/Mn), of 1.6, the terminal hydroxyl group thereof wasethenyloxyethylated using 2-chloroethylethenylether instead ofchloromethylstyrene in the “Preparation of PPE-1” to give a modifiedPPE. The modified PPE had a number averaged molecular weight of about2,500 as determined by gel permeation chromatography. Hereinafter, thePPE thus obtained will be referred to as “PPE-4”.

Preparation of Low Molecular Weight PPE (PPE-5)

Using a low molecular weight PPE of Asahi Kasei Corporation having anumber averaged molecular weight (Mn) of 2,100 and a ratio of weightaverage molecular weight (Mw) to number averaged molecular weight (Mn),(Mw/Mn), of 1.6, the terminal hydroxyl group thereof wasp-ethenylbenzylated using p-chloromethylstyrene (CMS-14, Seimi ChemicalCo., Ltd.) instead of the 50/50 mixture of p-chloromethylstyrene andm-chloromethylstyrene in the Preparation of PPE-1′ above to give amodified PPE. The modified PPE had a number averaged molecular weight ofabout 2,500 as determined by gel permeation chromatography. Hereinafter,the PPE thus obtained will be referred to as “PPE-5”.

Preparation of Low Molecular Weight PPE (PPE-6)

Using a low molecular weight PPE of Asahi Kasei Corporation having anumber averaged molecular weight (Mn) of 3,500 and a ratio of weightaverage molecular weight (Mw) to number averaged molecular weight (Mn),(Mw/Mn), of 1.9, the terminal hydroxyl group thereof wasethenylbenzylated in a similar manner to the “Preparation of PPE-1” togive a modified PPE. The modified PPE had a number averaged molecularweight of about 4,200 as determined by gel permeation chromatography.Hereinafter, the PPE thus obtained will be referred to as “PPE-6”.

Example 1

70 Mass parts of an ethenylbenzylated low molecular weight PPE, “PPE-1”,and 100 mass parts of toluene used as a solvent were mixed and stirredat 80° C. for 30 minutes until complete dissolution. To the PPE solutionthus obtained, 30 mass parts of TAIC (Nippon Kasei Chemical Co., Ltd.)as a crosslinking curing agent, 20 mass parts of a brominated organiccompound, decabromodiphenyl ethane (Albemarle Asano Corporation; brandname: “SAYTEX 8010”, Br-content: 82 wt %) as a flame retardant, and 2.5mass parts of α,α′-bis(t-butylperoxy-m-isopropyl)benzene (NOFCorporation; brand name: “Perbutyl P”) as a reaction initiator wereadded. Additionally, 14 mass parts of spherical silica (Denki KagakuKogyo Kabushiki Kaisha; brand name: “FB3SDC”) was added thereto as aninorganic filler, and the mixture was mixed, dispersed, and dissolved ina solvent (toluene) to give a resin composition, varnish. As the flameretardant is a brominated organic compound nonreactive with PPE andTAIC, the flame retardant was not completely dissolved and dispersed inthe resin composition, varnish.

Subsequently, the varnish was impregnated into an NE-type glass cloth(Nitto Boseki Co., Ltd.; brand name: “NEA 2116”), and the impregnatedcloth was heated and dried under a condition of a temperature of 120° C.and a period of 3 minutes to remove the solvent to give a prepreg havinga resin content of 55 mass % (sample (i)).

On both faces of a sheet of this prepreg, two copper foils (ST foil)having a thickness of 35 μm were placed, and heat-pressed under acondition of a temperature of 200° C. and a pressure of 3.0 MPa (30kg/cm²) for 180 minutes to give a double-sided copper-clad laminate foruse as an internal layer printed wiring boards. Then, after a wiringpattern was formed on the double-sided copper-clad laminate for use asan internal layer printed wiring board, the surface of copper foils wasblackened to give core printed wiring boards. The two core printedwiring boards were piled together, between the two core printed wiringboards and on their both surface, the three prepregs were placedrespectively. And additionally two sheets of copper foils (ST foil)having a thickness of 35 μm were placed on the utmost outer layers ofthe resulting stack. The resulting multi-layered stack was thenheat-pressed under a condition of a temperature of 200° C. and apressure of 3.0 MPa (30 kg/cm²) for 180 minutes to give a 6-layeredcopper-clad laminate for use as a printed wiring board. Subsequently,the 6-layered copper-clad laminate thus obtained was cut into pieceswith a dimension of 50 mm×50 mm, and the outer copper foil layersthereof were removed by etching to give samples for evaluation of theheat resistance, moisture resistance and processability of the 6-layeredboard. The 6-layered boards were cut to be 100 mm×10 mm pieces, and theywere used as samples for evaluation of the adhesion strength of theinternal layer copper foil (sample (ii)).

Separately, 7 sheets of prepregs were piled together and two copperfoils (ST foil) having a thickness of 35 μm were place on the top andbottom surfaces of the stack.

The resulting stack was heat-pressed under a condition of a temperatureof 200° C. and a pressure of 3.0 MPa (30 kg/cm²) for 180 minutes to givedouble-sided copper-clad laminates for use as printed wiring boards.Then, the double-sided copper-clad laminates thus obtained were cut intopieces with a diameter of 100 mm×10 mm to give samples for evaluatingcopper foil adhesion strength, and pieces with a diameter of 86 mm×86mm, on which a wiring pattern was formed, to give samples formeasurement of dielectric constant and dielectric dissipation factor.Further, the copper foils on both surface thereof were remove byetching, giving samples for evaluation of glass transition point (Tg),thermal expansion coefficient, flame resistance, and hygroscopicity(sample (iii)).

Separately, through holes having a drilling diameter of 0.25 mm weremade in FR-4 substrates having a thickness of 1.6 mm. After the throughholes were plated to a 20 μm thickness two prepregs and then two copperfoils a top thereof were stacked on both faces of the substrate, and thestack was heat-pressed under a condition of a temperature of 200° C. anda pressure of 3.0 MPa (30 kg/cm²) for 180 minutes. The resulting sheetswere used as the sample boards for evaluation of resin hole-fillingproperty into IVH (sample (iv)).

After a wiring pattern is formed on one side of the double-sidedcopper-clad laminates prepared in the step for preparing sample (ii) foruse as internal layer printed wiring board, a sheet of prepreg and thesame copper foil as used for making the double-sided copper-cladlaminates were stacked on the side, on which the wiring pattern wasformed, and the stack was heat-pressed under the same condition to givemultilayer printed wiring boards having strip lines (sample (v)).

Examples 2 to 9

By using the ingredients in the composition shown in Tables 1 and 2,prepregs and samples (i) to (v) were prepared in a similar manner toEXAMPLE 1. Incidentally, the unmodified PPE having a number averagedmolecular weight of about 9,000, which was added in EXAMPLE 9, wasprepared by the molecular degrading technique described above from a PPE(GE PLASTICS Japan Ltd.: brand name “Noryl PX9701”) having a numberaveraged molecular weight of 14,000.

Comparative Examples 1 and 2

By using the ingredients in the composition shown in Table 2, prepregsand samples (i) to (v) were prepared in a similar manner to EXAMPLE 1.

The materials used in Tables 1 and 2 are as follows:

Unmodified PPE: “Noryl PX9701”, GE PLASTICS Japan Ltd. (Mn: about14,000)

Crosslinking Curing Agent 1: Triallyl Isocyanurate (TAIC)

Crosslinking curing agent 2: Trimethylolpropane trimethacrylate (TMPT,Shin Nakamura Chemical Co., Ltd.; “NKester TMPT”)

Reaction initiator: α,α′-bis(t-butylperoxy-m-isopropyl)benzene (NOFCorporation; brand name: “Perbutyl P”)

Flame retardant: Decabromodiphenylethane (Albemarle Asano Corporation;brand name: “SAYTEX 8010”, Br content: 82 wt %)

Inorganic filler (spherical silica): Denki Kagaku Kogyo KabushikiKaisha, “FB3SDC”

The copper foil used had a surface roughness of 6 μm (Japan EnergyCorporation; “JTW”). In addition, the surface of the copper foil wasplated with zinc or a zinc alloy and additionally treated with acoupling agent.

EXPERIMENTAL EXAMPLE

The resin content and resin fluidity of prepregs were measured usingsamples (i) prepared in EXAMPLEs 1 to 4 and COMPARATIVE EXAMPLEs 1 and2; the glass transition point (Tg), dielectric constant, dielectricdissipation factor, thermal expansion coefficient, flame resistance,copper foil adhesion strength, and hygroscopicity, samples (iii) above;the secondary processability, solder heat resistance after moistureabsorption, and internal layer copper foil adhesion strength, samples(ii) above; the resin hole-filling property into IVH, samples (iv)above; and the transmission loss, samples (v) above.

The resin content and resin fluidity of prepregs were measured accordingto JIS (C6521); the dielectric constant, dielectric dissipation factor,copper foil adhesion strength of laminated sheets, JIS (C6481); thethermal expansion coefficient (z-axis), TMA method; the flameresistance, UL94 Standard; and the glass transition point (Tg), by usinga viscoelasticity spectrometer. The secondary processability wasdetermined by visual observation, based on the presence of the voids andscratches, after the outer layer copper foil previously subjected tosecondary processing was removed by etching. The internal layer copperfoil adhesion strength was the adhesion strength of the blackenedsurface.

The hygroscopicity was determined under a condition ofE-24/50+C-24/60/95. That is, the hygroscopicity was measured after thesamples were dried at 50° C. for 24 hours, cooled to 23° C. for 24hours, and stored at 95% relative humidity at 60° C. for 24 hours.Laminated sheet samples cut into pieces having a dimension of 50 mm×50mm after the surface thereof was removed by etching were used forhygroscopicity measurement.

The solder heat resistance after moisture absorption was determined inthe following manner: first, the 50 mm×50 mm 6-layered copper-cladlaminate samples were treated under D-2/100, i.e., boiled at 100° C. for2 hours and subjected to the Pressure Cooker test (PCT) wherein thesamples were treated at 135° C. under 2 atom (0.2 MPa) for 2 hours,respectively; 5 pieces of the samples were immersed in liquid solder at260° C. for 20 seconds; and the degree of measling and blister wasdetermined by visual observation. The resin hole-filling property intoIVH was determined in the following way: samples were first subjected to300 cycles of heating and cooling in the heat cycle test (condition B);the presence of voids and scratches were determined by visualobservation of the cross-section of the resin filled in IVH. Thetransmission loss was determined by measuring the transmission loss when1.6 GHz signals were applied to the internal layer circuit of themultilayer printed wiring boards.

The results from the measurements above are summarized in Tables 1 and2.

TABLE 1 EXAMPLE 1 2 3 4 5 PPE PPE-1 Mass Part 70 0 70 0 0 Resin Mn 2700— 2500 — — Warnish PPE-2 Mass Part 0 70 0 0 0 Mn — 2800 — — — PPE-3 MassPart 0 0 0 70 0 Mn — — — 2500 — PPE-4 Mass Part 0 0 0 0 70 Mn — — — —2500 Crosslinking kind TAIC TAIC TAIC TAIC TAIC Curing Agent 1 Mass Part30 30 20 30 30 Crosslinking kind — — TMPT — — Curing Agent 2 Mass Part —— 10 — — Reaction Initiator Mass Part 2.5 2.5 2.5 2.5 2.5 FlameRetardant Mass Part 20 20 20 20 20 Inorganic Filler Mass Part 14 14 1414 14 av. Diamter 3 3 3 3 3 (μm) Cu Foil Surface Roughness μm 6 6 6 6 6Prepreg Resin Content % 55 55 55 55 55 Resin Fluidity % 15 15 13 15 15Laminated Tg ° C. 218 222 236 230 225 Sheet Dielectric Constant 3.153.15 3.15 3.14 3.15 Dielectric 0.0015 0.0015 0.0015 0.0015 0.0015Dissipation Factor Thermal Expansion ppm/° C. 59 59 59 59 61 Coeff.(Z-axis) Flame Resistance UL Standard V-0 V-0 V-0 V-0 V-0 Cu Foil kN/m1.45 1.45 1.45 1.62 1.62 Adhesion Strength Sec. Processability OK OK OKOK OK Moisture Absorption % 0.33 0.33 0.33 0.33 0.33 Solder HeatResistance OK OK OK OK OK after Moisture Absorption Inner Layer Cu FoilkN/m 0.74 0.74 0.74 0.74 0.74 Adhesion Strength IVH Filling Ability OKOK OK OK OK Transmission Loss dB/m −6.0 −6.0 −6.0 −6.0 −6.0

TABLE 2 EXAMPLE COMPARATIVE 6 7 8 9 1 2 PPE PPE-1 Mass Part 0 0 0 0 0 0Resin Mn — — — — — — Warnish PPE-2 Mass Part 0 0 0 0 0 0 Mn — — — — — —PPE-3 Mass Part 0 0 70 60 70 70 Mn — — 2500 2500 14000 800 PPE-4 MassPart 0 0 0 0 0 0 Mn — — — — — — PPE-5 Mass Part 70 0 0 0 0 0 Mn 2500 — —— — — PPE-6 Mass Part 0 4200 0 0 0 0 Mn — — — — — — Unmodified Mass Part0 0 5 50 PPE Mn — — 14000 9000 Crosslinking kind TAIC TAIC TAIC TAICTAIC TAIC Curing Agent 1 Mass Part 30 30 30 40 30 30 Crosslinking kind —— — — — — Curing Agent 2 Mass Part — — — — — — Reaction Initiator MassPart 2.5 2.5 2.5 2.5 2.5 2.5 Flame Retardant Mass Part 20 20 20 20 20 20Inorganic Filler Mass Part 14 14 14 14 20 20 av. Diamter 3 3 3 3 3 3(μm) Cu Foil Surface Roughness μm 6 6 6 6 6 6 Prepreg Resin Content % 5555 55 55 56 56 Resin Fluidity % 15 11 13 8 2 25 Laminated Tg ° C. 235230 230 230 228 152 Sheet Dielectric Constant 3.14 3.14 3.14 3.25 3.203.22 Dielectric 0.0015 0.0014 0.0014 0.0017 0.0014 0.0016 DissipationFactor Thermal Expansion ppm/° C. 59 59 59 59 52 62 Coeff. (Z-axis)Flame Resistance UL Standard V-0 V-0 V-0 V-0 V-0 V-0 Cu Foil kN/m 1.371.62 1.62 1.47 0.96 0.64 Adhesion Strength Sec. Processability OK OK OKOK x x scratch scratch Moisture Absorption % 0.33 0.33 0.33 0.37 0.330.34 Solder Heat Resistance OK OK OK OK x x after Moisture Absorptionblister blister Inner Layer Cu Foil kN/m 0.69 0.74 0.74 0.64 0.44 0.31Adhesion Strength IVH Filling Ability OK OK OK OK x OK blister crackTransmission Loss dB/m −6.0 −6.0 −6.0 −6.3 −6.1 −6.1

As apparent from the results above, it was confirmed that the PPE resincompositions of EXAMPLEs 1 to 4, which are included in the scope of thepresent invention, have a glass transition point higher than those ofthe COMPARATIVE EXAMPLEs, wherein the number averaged molecular weightof the PPE used is outside the range specified by the present invention(less that 1,000 or more than 7,000), and are the material suitable forproduction of multilayer sheets, providing multilayer sheets having anexcellent humidity resistance and a solder heat resistances aftermoisture absorption. Moreover, the laminated sheets of EXAMPLEs,retaining dielectric characteristics almost identical with those ofCOMPARATIVE EXAMPLEs, have an superior heat resistance (solder heatresistance after moisture absorption), and the PPE resin compositions ofEXAMPLEs are superior in processability, especially in resin fillingproperty into IVH than those of the COMPARATIVE EXAMPLEs. In addition,sedimentation of the filler could be significantly suppressed in EXAMPLE8.

This application is based on Japanese Patent Application No. 2003-19475filed on Jan. 28, 2003 and No. 2003-136496 filed on May 14, 2003, thecontents of which are hereby incorporated by references.

Although the present invention has been fully described by way ofexample, it is to be understood that various changes and modificationswill be apparent to those skilled in the art. Therefore, unlessotherwise such changes and modifications depart from the scope of thepresent invention hereinafter defined, they should be construed as beingincluded therein.

1. A poly(phenylene ether) resin composition comprising a poly(phenyleneether) and a crosslinking curing agent containing trialkenylisocyanurate, wherein: said polyphenylene ether is represented by thefollowing formula (I), and the number averaged molecular weight thereofis in a range of 1,000 to 7,000;

[wherein, X is an aryl group; (Y)_(m) is a polyphenylene ether moiety;R¹ to R³ each independently is a hydrogen atom, an alkyl group, analkenyl group or alkynyl group; n is an integer of 1 to 6; and q is aninteger of 1 to 4] and a mass ratio represented by [the poly(phenyleneether)]/(the crosslinking curing agent) is 60/40 to 90/10.
 2. Thepoly(phenylene ether) resin composition according to claim 1, wherein nis
 1. 3. The poly(phenylene ether) resin composition according to claim1, wherein (Y)_(m) is represented by the following formula (II)

wherein, R⁴ to R⁷ each independently is a hydrogen atom, an alkyl group,an alkenyl group, an alkynyl group or an alkenyl carbonyl group; and mis an integer of 1 to
 100. 4. The poly(phenylene ether) resincomposition according to claim 1, wherein the portion represented by thefollowing formula is selected from p-ethenylbenzyl and m-ethenylbenzylgroups.


5. The poly(phenylene ether) resin composition according to claim 1,further comprising a poly(phenylene ether) having a number averagedmolecular weight in a range of 9,000 to 18,000.
 6. The poly(phenyleneether) resin composition according to claim 3, further comprising apoly(phenylene ether) having a number averaged molecular weight in arange of 9,000 to 18,000.
 7. The poly(phenylene ether) resin compositionaccording to claim 4, further comprising a poly(phenylene ether) havinga number averaged molecular weight in a range of 9,000 to 18,000.
 8. Thepoly(phenylene ether) resin composition according to claim 1, whereinboth p-ethenylbenzyl and m-ethenylbenzyl groups are present.
 9. Thepoly(phenylene ether) resin composition according to claim 1, whereinsaid crosslinking curing agent further contains a tri- topenta-functional (meth)acrylate compound.
 10. The poly(phenylene ether)resin composition according to claim 1, further comprising at least onekind of organic or inorganic filler.
 11. The poly(phenylene ether) resincomposition according to claim 10, wherein said filler has an averagediameter of 10 μm or less.
 12. The poly(phenylene ether) resincomposition according to claim 10, wherein said filler is a hollowsubstance.
 13. The poly(phenylene ether) resin composition according toclaim 10, wherein said filler is a substance prepared from afluorine-containing compound.
 14. The poly(phenylene ether) resincomposition according to claim 1, further comprising a flame retardant.15. The poly(phenylene ether) resin composition according to claim 14,wherein said flame retardant is a bromine compound having a brominecontent of 8 to 20 mass % with respect to the total amount of thecomposition.
 16. A prepreg prepared by impregnating the poly(phenyleneether) resin composition according to claim 1 into a substrate andsemi-curing the resulting impregnated substrate.
 17. The prepregaccording to claim 16, wherein said substrate is an NE-type glass cloth.18. A laminated sheet prepared by piling the prepreg according to claim16 and copper foil(s) one over the other under heat-pressing.
 19. Thelaminated sheet according to claim 18, wherein said copper foil has asurface roughness of 2 μm or less, and the surface thereof facing theprepreg is treated with zinc or a zinc alloy and at the same timecoupled with a silane coupling agent having a vinyl group.